1. Field of the Invention
The invention relates to processing unsolicited electronic mail. More particularly, this invention relates to classifying electronic mail into multiple directories based upon their spam-like properties.
2. Description of the Background Art
Electronic mail (“e-mail”) is a common form of communication for many individuals and most organizations throughout the world. Unfortunately however, e-mail recipients are often the targets of unsolicited mass mailings sent by mass marketers offering their products or services. Reminiscent of excessive mass solicitations via postal services, facsimile transmissions and telephone calls, an e-mail recipient may receive hundreds of unsolicited e-mails over a short period of time. Similar to the task of handling “junk” postal mail and faxes, an e-mail recipient must laboriously sift through his or her incoming mail simply to sort out the unsolicited “junk” e-mail from legitimate e-mails. Such unsolicited “junk” e-mail is in common parlance referred to as “spam”.
Many vendors of electronic mail servers, as well as many third-party vendors, offer spam-blocking software to detect, label and sometimes automatically remove spam. Presently, there exist many methods for detecting, labeling and removing spam. Representative methods are taught in the following U.S. patents, the disclosures of which are hereby incorporated by reference herein:
Pat. No.Title5,999,932System and Method for Filtering Unsolicited ElectronicMail Messages Using Data Matching and HeuristicProcessing6,023,723Method and System for Filtering Unwanted Junk E-MailUtilizing a Plurality of Filtering Mechanisms6,029,164Method and Apparatus for Organizing and AccessingElectronic Mail Messages Using Labels and full Text andLabel Indexing6,092,101Method for Filtering Mail Messages for a Plurality of ClientComputers Connected to a Mail Service System6,161,130Technique Which Utilizes a Probalistic Classifier to Detect“Junk” E-Mail by Automatically Updating A Training andRe-Training the Classifier Based on the Updated TrainingList6,167,434Computer Code for Removing Junk E-Mail Messages6,199,102Method and System for Filtering Electronic Messages6,249,805Method and System for Filtering Unauthorized ElectronicMail Messages6,266,692Method for Blocking All Unwanted E-Mail (Spam) Using aHeader-Based Password6,324,569Self-Removing Email Verified or Designated as Such by aMessage Distributor for the Convenience of a Recipient6,330,590Preventing Delivery of Unwanted Bulk E-Mail6,421,709E-Mail Filter and Method Thereof6,484,197Filtering Incoming E-Mail6,487,586Self-Removing Email Verified or Designated as Such by aMessage Distributor for the Convenience of a Recipient6,493,007Method and Device for Removing Junk E-Mail Messages6,654,787Method and Apparatus for Filtering E-Mail
As taught by several of the above-referenced patents, there exist spam filters that grade the spaminess of incoming e-mail by processing the e-mail for spam-like properties along a scale (e.g. 0-100) and if the incoming e-mail is graded to have a spaminess level above a predetermined numeric threshold (e.g., above 80), the e-mail is automatically moved from the recipient's Inbox into a spam directory. Ideally, all of the spam will be moved to the spam directory, thereby obviating the need for the recipient to read the e-mail in the spam directory. As used herein, the term “spaminess” may include undesired or unsolicited e-mails determined on a variety of objective and subjective scales including but not limited to politics, pornography and marketing scams.
Many algorithms exist for processing incoming e-mail and grading the spaminess of the e-mail. Some representative algorithms are taught in the foregoing patents whereas others are taught in the following publications, the disclosures of which are hereby incorporated by reference herein.
Hooman Katirai, Filtering Junk E-Mail: A Performance Comparisonbetween Genetic Programming and Naïve Bayes, Sep. 10, 1999.Jefferson Provost, Naïve-Bayes vs. Rule-Learning in Classification ofEmail, Technical Report AI-TR-99-284.Mehran Sahami, Susan Dumais, David Heckerman & Eric Horvitz, ABayesian Approach to Filtering Junk E-Mail, www.paulgram.comPaul Graham, Stopping Spam, August 2003, www.paulgram.comPaul Graham, So Far So Good, August 2003, www.paulgram.comPaul Graham, Filters That Fight Back, August 2003, www.paulgram.comPaul Graham, Better Bayesian Filtering, January, 2003,www.paulgram.com
Unfortunately, it is often the case that the predetermined threshold, coupled with the inherent inaccuracies of the algorithm employed for grading of the incoming e-mail for spaminess, results in some e-mail being misclassified as spam when it is not, or visa versa. Obviously, as incoming mail is assigned a high score based upon its level of spaminess, the likelihood of classifying incoming e-mail as spam increases as the threshold is decreased. However, this disadvantageously results in a greater likelihood of non-spam e-mails being misclassified as spam and consequently being overlooked and not read by the recipient. Conversely, increasing the threshold decreases the chance that non-spam e-mails are misclassified as spam.
The use of a spaminess threshold thus results in a paradox of being, on the one hand, too guarded of potentially misclassifying non-spam e-mails as spam by raising the threshold too high whereupon a significant number of spam e-mails would fail to be identified as spam and remain in the recipient's Inbox and, on the other hand, being too aggressive by reducing the threshold resulting in non-spam e-mails being classified as spam. Consequently, the recipient is often faced with the dilemma of having an inbox with significant amounts of spam or having to frequently scan the presumed spam e-mail in the spam directory to verify that a legitimate e-mail was not improperly moved to the spam directory.
Therefore, it is an object of this invention to provide an improvement which overcomes the aforementioned inadequacies of the prior art and provides an improvement which is a significant contribution to the advancement of the art of filtering spam.
Another object of this invention is to provide an apparatus and method for handling incoming e-mail based upon the e-mail's spam-like properties.
Another object of this invention is to provide an apparatus and method for grading incoming e-mail for spaminess and, based upon the e-mail's spaminess grade, moving the incoming e-mail to at least one of a plurality of appropriately labeled directories.
The foregoing has outlined some of the pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.